Process for the production of alkyleneglycol esters

ABSTRACT

IN THE PROCESS OF PRODUCING AN ALKYLENEGLYCOL ESTER OF ORGANIC CARBOXYLIC ACID WHICH COMPRISES REACTING A HIGHER ORGANIC CARBOXYLIC ACID WITH AN ALKYLENE OXIDE IN THE PRESENCE OF AN OXYALKYLATION CATALYST UNDER OXYALKYLATION CONDITIONS AND RECOVERING SAID ALKYLENE GLCOL ESTER, THE IMPROVEMENT WHICH COMPRISES USING A HIGH MOLECULAR WEIGHT AMINE:OXIDE OR A DIAMINE HDIOXIDE OF SAID OXYALKYLATION CATALYST IN THE REACTION OF A HIGHER ORGANIC CARBOXYLIC ACID WITH THE ALKYLENE OXIDE.

United States Patent US. Cl. 260410.6 8 Claims ABSTRACT OF THEDISCLOSURE In the process of producing an alkyleneglycol ester oforganic carboxylic acid which comprises reacting a higher organiccarboxylic acid with an alkylene oxide in the presence of anoxyalkylation catalyst under oxyalkylation conditions and recoveringsaid alkylene glycol ester, the improvement which comprises using a highmolecular weight amine-oxide or a diamine dioxide of said oxyalkylationcatalyst in the reaction of a higher organic carboxylic acid with thealkylene oxide.

CROSS REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of copending application Ser. No. 889,753, filedDec. 31, 1969, and

now abandoned.

THE PRIOR ART It is known that the prior art processes of oxyalkylationof carboxylic acids carried out in the presence of basic oxyalkylationcatalysts are generally not suitable for the preparation of themono-esters of alkyleneglycols, since the diester formation is promotedboth (1) from the alkyleneglycol carboxylic acid mono-esters andunreacted carboxylic acid present, and also (2) by rearrangement of thealkyleneglycol carboxylic acid mono-esters formed to diesters andpolyalkyleneglycol. It has therefore already been proposed to use othercatalysts in the process of oxyalkylation of carboxylic acids. The US.Patent Specification No. 2,910,490 describes a process for thepreparation of alkyleneglyool carboxylic acid mono-esters by reactingcarboxylic acids with alkylene oxides using ammonium halides ascatalysts. In the German Auslegeschrift 1,248,660, thioethers areproposed as catalysts for the same purpose. From the Dutch PatentApplication No. 6614650 the use of sulfoxides and from the GermanAuslegeschrift Nos. 1,154,479 and 1,157,623 the use of aqueouscarboxylic acid amides as catalysts for the said reaction is known.

With reference particularly to the use of the alkyleneglycol carboxylicacid mono-esters as starting substances for the preparation ofsurface-active compounds of the sulfate type, the said catalysts havedisadvantages which make their separation necessary. Thioethers andsulfoxides have, and give on oxyalkylation, an unpleasant odor. Ammoniumhalides, especially those with relatively long alkyl residues, formundesired neutral salts in admixture with anionic surface-activecompounds. Finally, carboxylic acid amides may lead to trouble duringthe oxyalkylation process, since they begin to hydrolyze at atemperature of about 100 C. and can also give rise to side reactions.

In U.S. Pat. 3,360,545 it is known to prepare bis(hydroxyalkyl)fumarates by the catalyzed reaction of alkylene oxides with fumaric acidin a solvent with the reaction run until a product having an acid numberof preferably five to fifteen is obtained. The oxyalkylation caticealyst is selected from a group of basic catalysts including lowmolecular weight amine oxides, such as trimethylamine oxide. Adisadvantage of this process is that if the reaction is not terminatedat the proper time and if the reaction therefore continues until theacid number of the product drops below about five, then a large amountof alkylene glycol bis(alkyl fumarate) begins to form. The presence ofalkylene glycol bis(alkyl fumarate) renders the product blend unsuitablefor subsequent use as a monomer in polymerization reactions, since itcauses undesirable crosslinking reactions.

From US. Pat. 3,481,973 it is known to prepare alkyl hydroxyalkylfumarates by the catalyzed reaction of alkylene oxides with alkylhydrogen fumarates, in which the oxyalkylation catalyst is selected froma group of nucleophilic catalysts including heterocyclic amine oxides,such as pyridine N-oxide, and low molecular weight alkylamine oxides,such as trimethylamine N-oxide, triethylamine N- oxide, andtripropylamine N-oxide. The reaction is run until a product having anacid number no lower than two is obtained. A disadvantage of thisprocess is that if the reaction is not terminated at the proper time andif the reaction therefore continues until the acid number of the productdrops below about two, then a large amount of alkylene glycol bis(alkylfumarate) begins to form. The alkylene glycol bis (alkyl fumarate)renders the product blend unsuitable for subsequent use as a monomer inpolymerization reactions, since it causes undesirable crosslinkingreactions.

OBJECTS OF THE INVENTION It is an object of the present invention toprovide a process for the oxyalkylation of higher carboxylic acidsutilizing as the oxyalkylation catalyst certain amine-oxides ordiamine-dioxides, such that products are obtained with very low amountsof polyalkylene glycol and diester formation and with high amounts ofmonoester formation, which products can be directly sulfated withoutisolation of the catalyst.

It is another object of the present invention to provide a developmentin the process of producing an alkylene glycol ester of an organiccarboxylic acid which comprises reacting an organic carboxylic acid withan alkylene oxide in the presence of an oxyalkylation catalyst underoxyalkylation conditions and recovering said alkylene glycol ester, theimprovement which consists of reacting an organic carboxylic acid havingfrom 6 to 26 carbon atoms with an alkylene oxide in the presence of anamine-oxide oxyalkylation catalyst having the formula wherein R and Rare selected from the group consisting of alkyl having from 1 to 24carbon atoms, R is lower alkyl, R, is alkylene having from 2 to 24carbon atoms and R is alkyl having 8 to 24 carbon atoms.

These and other objects of the invention will become apparent as thedescription thereof proceeds.

DESCRIPTION OF THE INVENTION The present invention is directed to adevelopment in the process of producing an alkylene glycol ester of anorganic carboxylic acid which comprises reacting an organic carboxylicacid with an alkylene oxide in the presence of an oxyalkylation catalystunder oxyalkylation conditions and recovering said alkylene glycolester, the improvement which consists of reacting an organic carboxylicacid having from -6 to 26 carbon atoms with an alkylene oxide in thepresence of an amine-oxide oxyalkylation catalyst having the formulawherein R and R are selected from the group consisting of alkyl havingfrom 1 to 24 carbon atoms, R, is lower alkyl, R, is alkylene having from2 to 24 carbon atoms and R is alkyl having 8 to 24 carbon atoms.

An improvement in the process of oxyalkylation of carboxylic acids hasnow been discovered. This improvement comprises utilizing a carboxylicacid of 6 to 26 carbon atoms as the fatty acid reactant and utilizing ahigh molecular weight amine oxide or diamine dioxide as theoxyalkylation catalyst. The use of this amine-oxide or diamine dioxidecatalyst results in production of alkyleneglycol esters of higherorganic carboxylic acid containing from 80% to 99% of monoesters, basedon the alkyleneglycol, without resulting in the production of apolyglycol reaction product.

The amine-oxide catalysts of the invention are oxides of tertiary amineswhich may be cyclic and may be depicted by the formula wherein the Rsrepresent aliphatic residues preferably with from 1 to 24 carbon atoms,cycloaliphatic, heterocyclic and/or aromatic residues as well ascorresponding diand polyfunctional amine-oxide in which the amineoxidegroupings are linked by divalent aliphatic residues.

wherein R and R are selected from the group consisting of alkyl havingfrom 1 to 24 carbon atoms, R is lower alkyl, R, is alkylene having from2 to 24 carbon atoms and R is alkyl having 8 to 24 carbon atoms.

Examples of amine-oxides utilizable according to the invention include:dimethyldodecylamine-oxide, dimethyloctadecylamine-oxide,dioctadecylmethylamine-oxide, N,N,N',N-tetramethylethylenediamine-dioxide, N,N,N',N'tetramethyldodecamethylenediamine-dioxide. Amine-oxides are preferablyused which contain at least one aliphat-, ic residue with 8 to 24 carbonatoms and therefore may have detergent properties.

The amine-oxides to be used as catalysts according to the invention canbe prepared in the known way, for example by reacting corresponding monoand polytertiary amines with hydrogen peroxide in aqueous solution.

The amine-oxides may be present in the oxyalkylation reaction both inanhydrous form and in the form of an aqueous paste, such as is formed inthe known method of preparation.

Since the said catalysts as described above may remain in the endproduct, the amount of catalyst to be used is not critical and may varywithin wide limits. A proportion of from 1% to 5% by weight ofamine-oxide, based on the higher carboxylic acid used, is generallysutficient for carrying out the reaction. However, the proportion mayalso be chosen so that, after sulfating the products, a surface-activecombination of amine-oxides and ester sulfates directly utilizable inpractice is present, which in some respect, for example with referenceto detergent action and skin compatibility, show more favorableproperties than the ester sulfates alone. In liquid surface-activecombinations the amine-oxides also act as regulators of viscosity.

The process, according to the invention, is applicable to higher monoand poly-carboxylic acids, which may be saturated or unsaturated,straight or branched chain, ali phatic, cycloaliphatic, aromatic orheterocyclic with preferably 6 to 26 carbon atoms. Examples of suchstarting substances are alkanoic acids having 8 to 26 carbon atoms suchas lauric acid, stearic acid, etc., alkenoic acids having from 8 to 24carbon atoms, alkadienoic acids having from 8 to 24 carbon atoms,hydroxyalkenoic acids having from 8 to 24 carbon atoms, all such as maybe obtained from natural fats and oils by saponification, as well asmixtures thereof, cycloalkylcarboxylic acid having from 6 to 24 carbonatoms, such as cyclohexanecarboxylic acid, phenylcarboxylic acids havingfrom 7 to 24 carbon atoms such as benzoic acid, terephthalic acid, etc.,alkanedioic acids having from 8 to 24 carbon atoms such as octanedioic,etc., and dimeric and oligomeric fatty acids having from 24 to 56 carbonatoms as obtained by polymerization of unsaturated higher fatty acids.In addition to the above, mixtures of higher organic carboxylic acids asobtained by oxidation of hydrocarbons and carbonylation of olefinic oracetylenic hydrocarbon by known processes may be utilized.

The alkylene oxides utilized in the process are vicinal alkylene oxideshaving from 2 to 4 carbon atoms of the formula Rr-CH C H-R wherein R isa member selected from the group consisting of hydrogen, methyl, ethyl,halomethyl and hydroxymethyl, for example ethylene oxide, propyleneoxide, butylene oxide, epichlorhydrin or glycide.

The alkylene oxides are used in substantially the stoichiometricamounts, that is, n mol of epoxide are used per mol of n-valent highercarboxylic acid. However, a small excess of epoxide may be advantageous.

The reaction of the higher carboxylic acids with the epoxides may becarried out under the usual conditions for oxyalkylation processes.Consequently, temperatures between 20 C. and 200 C., preferably between40 C. and 100 C. may be used, and the process may be carried out both atnormal pressures and, e.g. in an autoclave, under a slightly increasedpressure.

The use of a solvent is generally unnecessary. In some cases, however,for example in the reaction of highmelting carboxylic acids, the use ofa solvent usual for oxyalkylation reactions, for examplediethyleneglycoldimethyl ether or dioxan, may be of advantage.

In order to carry out the reaction, to the higher organic carboxylicacid or, in certain cases, the higher carboxylic acid-solvent mixture,is added the required amount of catalyst, the subsequent mixture isheated to the desired reaction temperature and, after driving the airout of the reaction vessel, the calculated amount of alkylene oxide isadded in liquid or gaseous form. The reaction products obtained arewater-white and have mono-ester contents between and 99%. The remaining20% to 1% consists of some unreacted carboxylic acid and diester.

It is not necessary to terminate the reaction before the acid number ofthe product drops below about five, as in US. Pat. 3,360,545; or beforethe acid number of the product drops below two, as in US. Pat.3,481,973. Polyglycol is practically absent from the products. Thedetermination of the contents of mono-ester, diester and polyglycol iseffected according to the directions given by Malkemus and Swan in theJournal of the American Oil Chemists Society, 34, pages 342 onwards.Owing to the high mono-ester content and the fact that the amide-oxidesused as catalysts can remain in the reaction mixture without causingtrouble, working up of the products of the process is generallyunnecessary.

When low molecular weight amine oxides such as trimethylamine-oxide areemployed, even with higher molecular weight carboxylic acids, an undulyhigh amount of diesters are formed, as compared with the use of thehigher molecular weight amine-oxides. In addition, when lower carboxylicacids are alkoxylated, even with the higher molecular weight amine oxidecatalysts, again high amounts of unwanted diesters are formed, alongwith higher amounts of unwanted polyalkylene glycols.

The following specific embodiments are illustrative of the practice ofthe invention without being deemed limitative in any respect.

EXAMPLE 1 200 gm. (1 mol) of lauric acid were placed in an autoclave of5 liters capacity and 4 gm. (2% by weight) of anhydroustrimethylamine-oxide were added thereto. The air in the autoclave wasremoved by flushing with nitrogen. After the contents of the autoclavehad been heated to 70 (3., a total of 44 gm. (1 mol) of ethylene oxidewas introduced from a stock vessel by the aid of nitrogen at a pressurebetween 0.8 and 9 atmospheres. During the reaction the temperatureremained between 70 C. and 80 C. The measured quantity of ethylene oxideintroduced was absorbed in the course of 3.5 hours. The resultingproduct was waterwhite and contained 87.4% by weight of mono-ester, 9.0%by weight of diester and 3.6% by weight of unreacted lauric acid;polyethylene glycol was not detectable. (In calculating the data for thecomposition of the product, the content of catalyst was mathematicallyeliminated.)

EXAMPLES 2 TO 14 The procedures relating to the examples summarized inthe following Table I were carried out as in Example 1. 1 mol ofcarboxylic acid was used in each case. In all the data for thecomposition of the end product, the content The advantages attainablethrough the invention, in addition to the possibility of obtainingalkyleneglycol mono-esters of higher carboxylic acids in high yields,consist principally in that separation of the catalyst, and therefore inmost cases working up of the reaction mixture can be omitted. Thealkyleneglycol carboxylic acid mono-esters have, therefore, becomeavailable in a substantially more economic way, without containing anypolyglycol.

When the products of the process are subsequently sulfated, the presenceof amine-oxides has been found specially advantageous, sinceamine-oxides form adducts with the sulfating agent, for example S0 orchlorosulfonic acid, and therefore the reaction goes economically.

The sulfation products show a better color quality, a high degree ofsulfation and a low content of by-products because side reactions, suchas ester exchange reactions which are known to be catalyzed by Lewisacids, are substantially eliminated. The amine-oxide sulfate adducts aresplit up again when the sulfation mixtures are neutralized withformation of the originally introduced amine-oxides.

The preceding specific embodiments are illustrative of the practice ofthe invention. It is obvious, however, that other expedients known tothose skilled in the art may be employed without departing from thespirit of the invention or the scope of the appended claims.

We claim:

1. In the process of producing an alkylene glycol ester of an organiccarboxylic acid which comprises reacting an organic carboxylic acid withan alkylene oxide in the presence of an oxyalkylation catalyst underoxyalkylation conditions and recovering said alkylene glycol ester, theimprovement which consists of reacting an organic carboxylic acid havingfrom 6 to 26 carbon atoms with an alkylene oxide in substantially thestoichiometric amounts and in the presence of an amine-oxideoxyalkylation catalyst selected from the group consisting of (A) anamine-oxide selected from the group consisting of dimethyldodecylamineoxide, dimethyloctadecylamineoxide, and dioctadecylmethylamine-oxide,and (B) an amine oxide having the formula of catalyst was mathematicallyeliminated. In Examples R: R, 13 and 14 the analysis of the end productwas effected l l 1 4N i respectlvely, spectrographically by nuclearmagnetic l l resonance and by distillation. O 0

TABLE I Composition of the end product, percent Reaction conditions Molsand type Poly- Carbox- Catalyst (percent wt.) in the end Temp, Pressure,Time, of alkylene Mono- Dialk'ylene Example No. yhc acid product 0. atm.hours oxide added Acid ester ester glycol 2 Laurie 1.9%dimethyldodecylamineoxide (an- 75-76 0.7-8.1 11.5 1.1 ethylene 0 94.45.6 0

acid. hydrous oxide. 3 ..do 2.0% dimethyldodecylamine oxide 75-78 05-12512.5 1.0 ethylene 2.2 95.0 2.8 0

(85% aqueous paste). oxide. 4 .do 2.9% dimethyldodecylamine oxide 75-780.8-10.0 6.5 --.do 0.4 98.7 0.9 0

(85% aqueous paste). 2.0% dimethyloctadecylamine oxide 72-78 0.611.611.3 ...---do 2.9 95.0 2.1 0

(92% aqueous paste). .0% dioctadecylrnethyiamine oxide 82-85 0.5-11.04.8 do 6.7 88.4 4.9 0

(99% aqueous paste). 7 ..d0 2.0% N,N,N',N-tetramethylethy1ene- -770.6-10.8 8.2 ..do 2.0 93.4 4.6 0

diaminedioxide aqueous paste). 8 "do 2.0% N,N,Nf,N-tetramethy1dodeca-73-78 0.6-11.3 7.2 do 1.9 93.8 3.5 0.8

methylenediamine dioxide (81% aqueous paste). 9 -do 2.9%dimethyldodecylamine oxide 78-84 0.7-13.0 7.9 1.0 propylene 2.9 97.1 0 0(85% aqueous paste). oxide. 10 Stearle 2.9% dimethyldodecylamine oxide-83 0.510.0 5 do 0 100 0 0 acid aqueous paste). 11 Benzoie 2.9 0dimethyldodecylamine oxide 70-80 0.5-9.0 8.3 1.0 ethylene 5.0 93.2 0 1.8

act (85% aqueous paste). 0 e. 12 Fish 011 2.9% dimethyldodecylamineoxide 73-80 06-13.!) 14.7 1.0 butyiene 3.4 95.5 0 1.1

5010 (85% aqueous paste). oxide.

8.01 No. 201.8, Iodine No. 140.1). 13 Glutan'c 2.9% dimethyldodecylamineoxide 74-100 0.6-9.5 8.3 2.0 ethylene 3.0 87.0 9.0 1.0

acid. (85% aqueous paste). oxide. 14 Acetic 2.9% dimethyldodecylamineoxide 52-60 0.5-6.0 8.8 1.0 ethylene 9.4 76.0 12.5 2.1

acid. (85% aqueous paste). oxide. Mono-ester master }with reference toethylene glycol.

wherein R and R are alkyl having from 1 to 24 carbon atoms, and R isalkylene having from 2 to 24 carbon atoms, whereby the reaction productsobtained have a mono-ester content of between 80% and 99%.

2. The process of claim 1, in which the amine-oxide is selected from thegroup consisting of N,N,N,N'-tetramethylethylenediamine-dioxide andN,N,N',N-tetramethyldodecamethylenediamine-dioxide.

3. The process of claim 1 wherein said amine-oxide is present in anamount of at least 1% by weight, based on the weight of said organiccarboxylic acid.

4. The process of claim 3 wherein said amine-oxide is present in anamount of from 1% to 5% by weight, based on the weight of said organiccarboxylic acid.

5. The process of claim 1 wherein said organic carboxylic acid isselected from the group consisting of a fatty acid obtained from naturalfats and oils by saponification and mixtures of the same.

6. The process of claim 1 wherein said alkylene oxide is selected fromthe group consisting of ethylene oxide, propylene oxide and butyleneoxide.

7. The process of claim 1 wherein said organic carboxylic acid isselected from the group consisting of alkanoic acids having 8 to 26carbon atoms, alkenoic acids having 8 to 24 carbon atoms, alkadienoicacids having from 8 to 24 carbon atoms, hydroxy-alkenoic acids having 8to 24 carbon atoms, cycloalkyl carboxylic acids having 6 to 24 carbonatoms, phenylcarboxylic acids having 7 to 24 carbon atoms, andalkanedioic acids having 8 to 24 carbon atoms.

8. The process of claim 7 wherein the organic carboxylic acid isselected from the group consisting of lauric, stearic, and benzoicacids.

References Cited UNITED STATES PATENTS 12/1969 Wygant et al 260-48512/1967 Wygant 260-485 LEWIS GOTTS, Primary Examiner D. G. RIVERS,Assistant Examiner

